Sensorless motor driving device

Abstract

In a sensorless motor driving device for driving a motor by controlling the energization of the coils of individual phases of the motor according to the result of detecting the position of the rotor of the motor without using an external sensor, before the motor is started, which phase to energize first when the motor is started is determined according to the result of detecting the position in which the rotor is at rest by exploiting the fact that the coils of the individual phases have varying apparent inductances according to the position in which the rotor is at rest. This circuit configuration permits the motor to be started always in the same rotation direction, and thus prevents reverse rotation of the motor.

Description

BACKGROUND OF THE INVENTION [0001]1. Field of the Invention [0002] The present invention relates to a sensorless motor driving device for driving a motor by detecting the position of the rotor of the motor without using an external sensor such as a hole element and controlling the energization of the coils of individual phases of the motor according to the result of the detection. [0003]2. Description of the Prior Art [0004] First, taking up a two-phase half-wave motor driving device as an example, prior art will be described. FIG. 15 shows a block diagram of a conventional, common two-phase half-wave motor driving device 100′. A hole element H is arranged so as to face a rotor of a motor M. A comparator 101 outputs a binary signal that represents the relationship in magnitude between the voltages output from both ends of the hole element H. A commutation portion 102, according to the binary signal output from the comparator portion 101, decides which of two transistors T1 and T2, w...

AI Technical Summary

Benefits of technology

The present invention provides a sensorless motor driving device that prevents the motor from rotating backwards. This is achieved by detecting the position of the rotor when it is at rest and determining which phase to energize first when the motor is started. This ensures that the motor always starts in the same rotation direction and prevents reverse rotation. The device uses the fact that the coils of the individual phases have varying apparent inductances according to the position of the rotor to detect the position of the rotor at rest. This technology eliminates the need for an external sensor and improves the efficiency and reliability of motor driving.

Problems solved by technology

The problem with this conventional, common two-phase half-wave motor driving device is that it requires an external sensor (hole element) to detect the position of the rotor.

This has been hindering cost reduction and miniaturization.

However, in this sensorless driving method, when the rotor is at rest, no back electromotive force appears in the coil of each phase, and therefore the position of the rotor cannot be detected.

Thus, simply applying a drive signal to the motor when it is started may cause, quite inconveniently, the motor to start rotating in the reverse direction.

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